EP 1 140 693 B1 discloses a horse bit comprising a shackle configured to be inserted into a horse's mouth. In one embodiment a single jointed horse bit comprises two elongated side portions whose inner ends provide eyelets for interlocking and forming a joint similar to that seen in a chain-link system. This embodiment provides a single joint with free play to allow the mouthpiece to adopt a large range of positions within the mouth. In another embodiment a double jointed horse bit comprises two elongated side portions whose inner ends provide eyelets for joining loosely to a central portion which itself contains eyelets to receive the side portion eyelets to form two joints. This embodiment provides for two joints connecting the side portions to the central portion each having free play around a large range of 3-dimensional angles.
Horse bits of the prior art comprise two functional parts or groups of parts. The first part is the shackle which may comprise a system of jointed components or a single solid component configured to be inserted into the mouth of the horse. This part may also be designated as the mouthpiece part. The second parts are joined to and to either side of the shackle and lie outside of the mouth. These parts can also be designated as the cheeks. They are attached to bridlework such as reins, cheek-pieces, brow band etc. so that the mouthpiece or shackle can be mounted on the horse's head and so that forces from the rider through the attached reins can convey direction and speed commands to the horse.
Consideration of the configuration of these two separate parts or groups of parts gives the horse bit designer the opportunity to tailor the forces applied to the mouthpiece to achieve the desired objective.
The anatomical features of the mouth onto which these forces are applied are primarily the tongue, the roof of the mouth (palate) and the lip tissue lying to either side of the tongue. In most horses the tongue fills the oral cavity and any horse bit must therefore displace or compress the tongue so that it may be accommodated in the mouth if the mouth is to be closed. The lip tissue is similarly compressed if the mouth is closed. As a closed mouth is one of the desirable objectives in competitive equestrianism it is desirable that the bit is comfortable in the mouth when it is closed.
The surfaces of the mouthpiece components of the prior art horse bits comprise a circular or slightly elliptic shape when seen in a cross-section. The most common known cross-sectional profile of a shackle in the prior art is a circle but oval profiles are also commonly found. Most of these profiles may convert the applied forces into large pressures when the area of contact between the mouth and the shackle surface involves a profile with a small radius of curvature. Such a profile having a small radius of curvature acts like having a single point that makes the initial contact with the mouth tissue prior to any further compression of the tissue. Such single point contacts can lead to high contact pressure on the inner surfaces of the mouth and the discomfort this can produce in the horse causes it to relieve the pressure by opening its mouth.
It is an object of the invention to provide a horse bit comprising a shackle providing an improved distribution of the pressure onto the mouth tissue while still being comfortable within the horse's mouth. At the same time the bit should fit to the anatomy of the horse's mouth in a good manner and find good acceptance with the horse.